The invention relates to an internal combustion engine with a cooling system and exhaust gas recirculation system and with a coolant collecting rail extending alongside the engine for collecting the coolant from the areas around the various cylinders.
An internal combustion engine for a motor vehicle conventionally comprises an engine housing with a cylinder head, a plurality of cylinders and a plurality of coolant lines. The coolant lines are connected by means of at least one coolant inflow opening to a coolant pump for feeding a cooled coolant to the engine, and by way of at least one coolant outflow opening to a coolant collecting rail. The coolant collecting rail correspondingly has at least one first coolant inflow opening and a coolant outflow opening which is connected by means of a coolant line to a cooler for cooling the coolant. The coolant which is cooled in the cooler in this way is then returned to the coolant pump.
In an internal combustion engine with an exhaust gas recirculation (EGR) system, a part of the exhaust gases of the internal combustion engine can be supplied via an EGR line back to the intake duct of the internal combustion engine. An EGR heat exchanger for cooling the recirculated exhaust gas is arranged in the EGR line, and the EGR flow is controlled by means of an EGR valve which may likewise be cooled. The EGR heat exchanger and the EGR valve are therefore likewise constituents of the cooling system, and the EGR heat exchanger has a coolant inflow opening, which is connected to the coolant pump, and a coolant outflow opening. The coolant outflow opening of the EGR heat exchanger is connected to a second coolant inflow opening of the coolant collecting rail, so that all of the coolant of the cooling system is collected in the coolant collecting rail.
The cooling system of the internal combustion engine generally has further components, such as for example oil coolers, compensating tanks, thermostat valves, various pressure sensors and temperature sensors and the like, which are however not of significance for the present invention.
On account of the ever more restricted available installation space, there is demand for compact constructions for internal combustion engines of said type.
It is thus for example known from the documents DE 101 19 484 A1, JP-A-2000-248936 and JP-A-2002-030995 to mount the EGR heat exchanger directly on the cylinder head of the engine housing. In JP-A-2001-227414, the EGR valve is fastened directly to the cylinder head.
U.S. Pat. No. 6,478,017 discloses an internal combustion engine in which the complete EGR line including the EGR heat exchanger is integrated in the engine housing.
It is the object of the present invention to provide a compact and at the same time cost-effective arrangement of a cooling system and exhaust gas recirculation system of an internal combustion engine.